FACULTY OF CIVIL ENGINEERING AND BUILT
ENVIRONMENT
DEPARTMENT OF CIVIL ENGINEERING
TRANSPORTATION LABORATORY
FULL REPORT
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DEPARTMENT OF CIVIL ENGINEERING
FACULTY OF CIVIL ENGINEERING AND BUILT ENVIRONMENT
I, hereby confess that I have prepared this report on my own effort. I also admit not
to receive or give any help during the preparation of this report and pledge
that everything mentioned in the report is true.
Student Signature
Name
: …………………………………………
Matric No. : …………………………………………
Date
: …………………………………………
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
SOFTENING POINT OF BITUMEN
1.0 OBJECTIVE
To determine the softening point of bitumen within the range 30 to 157 º C by means of the
Ring-and-Ball apparatus.
2.0 BACKGROUND
Unlike some substances (e.g. water which changes from solid to liquid at 0 º C bituminous
materials do not have a definite melting point. Instead, as the temperature rises, these
materials slowly change from brittle or very thick and slow-flowing materials to softer and
less viscous liquids. For this reason, the determination of 'softening point' must be made
by a fixed, arbitrary and closely defined method if results are to be comparable.
Being very simple in concept and equipment, the Ring-and-Ball Test has remained a
valuable consistency test for control in refining operations, particularly in the production of
air-blown bitumens. It is also an indirect measure of viscosity or, rather, the temperature at
which a given viscosity is evident. The softening point value has particular significance for
materials which are to be used as thick films, such as joint and crack fillers and roofing
materials. A high softening point ensures that they will not flow in service. For a bitumen of
a given penetration (determined at 25 º C), the higher the softening point the lower
the temperature sensitivity
Research has shown that, for conventional paving grade bitumens, the Ring-and-Ball
softening point temperature is the same as that which would give a penetration of 800dmm. This, together with the penetration at 25 º C, can be used to compute the Penetration
Index.
3.0 SUMMARY OF TEST METHOD (ASTM 1988)
Two horizontal disks of bitumens, cast in shouldered brass ring are heated at a controlled
rate in a liquid bath each supports a steel ball. The softening point is reported as the mean of
the temperatures at which the two disks soften enough to allow each ball, enveloped in
bitumen to fall a distance of 25 mm.
1
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
SOFTENING POINT OF BITUMEN
4.0 PROCEDURE (Figure 1)
1. Select one of the following bath liquids and thermometers appropriate for the expected
softening point:
a) Freshly boiled distilled water for softening points between 30 and 80°C (86 and
176°F); use Thermometer 15C or 15F. The starting bath temperature shall be 5 6 1°C
(41 6 2°F).
b) USP glycerin for softening points above 80°C (176°F) and up to 157°C (315°F); use
Thermometer 16C or 16F. The starting bath temperature shall be 30 6 1°C (86 6 2°F).
c) Ethylene glycol for softening points between 30 and 110°C (86 and 230°F); use
Thermometer 16C or 16F. The starting bath temperature shall be 5 6 1°C (41 6 2°F).
d) For referee purposes, all softening points up to 80°C (176°F) shall be determined in a
water bath and all softening points above 80°C (176°F) shall be determined in a
glycerin bath.
2. Assemble the apparatus in the laboratory hood with the specimen rings, ball-centering
guides, and thermometer in position, and fill the bath so that the liquid depth will be 105
6 3mm (41⁄8 6 1⁄8 in.) with the apparatus in place. If using ethylene glycol, make sure the
hood exhaust fan is turned on and operating properly to remove toxic vapors. Using
forceps, place the two steel balls in the bottom of the bath so they will reach the same
starting temperature as the rest of the assembly.
3. Place the bath in ice water, if necessary, or gently heat to establish and maintain the
proper starting bath temperature for 15 min with the apparatus in place. Take care not to
contaminate the bath liquid.
4. Again using forceps, place a ball from the bottom of the bath in each ball-centering
guide.
5. Heat the bath from below so that the temperature indicated by the thermometer rises at a
uniform rate of 5°C (9°F)/min (Note 7). Protect the bath from drafts, using shields if
necessary. Do not average the rate of temperature rise over the test period. The maximum
permissible variation for any 1-min period after the first 3 min shall be6 0.5°C (6 1.0°F).
Reject any test in which the rate of temperature rise does not fall within these limits.
2
NOTE 7—Rigid adherence to the prescribed heating rate is essential to
reproducibility of results. Either a gas burner or electric heater may be used, but
the latter must be of the low-lag, variable output type to maintain the prescribed
rate of heating.
6. Record for each ring and ball the temperature indicated by the thermometer at the instant
the bitumen surrounding the ball touches the bottom plate. Make no correction for the
emergent stem of the thermometer. If the difference between the two temperatures
exceeds 1°C (2°F), repeat the test.
5.0 RESULTS
The mean temperature of the two specimens (which shall not differ by more than 10 C) is
recorded as the softening point. This temperature is to be used in conjunction with the
penetration value to obtained the Penetration Index (PI)
6.0 DISCUSSION
a)
b)
c)
d)
e)
State the heating rate of the liquid bath during the experiment
Quote the mean softening point of your specimen. Comment on the value obtained.
If the two test temperature differ by more than 1 ˚C, offer an explanation.
Explain the function of the magnetic stirrer
Report the possible grade of tested bitumen.
7.0 REFERENCES
1. ASTM (1998). ASTM D36-95 Standard test method for softening point of
bitumen (Ring and Ball Apparatus). 1998 Annual Book of ASTM Standards,
Volume 04.04, American Society for Testing and Materials, Philadelphia, PA 191031187
2. Millard, R.S. (1993). Road building in the tropics. Transport Research Laboratory Stateof-the-art Review 9, HMSO, London.
3
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
SOFTENING POINT OF BITUMEN
Apparatus for the Bitumen Softening Point Test (Millard, 1993)
4
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
SOFTENING POINT OF BITUMEN
RESULTS AND CALCULATION
TableA.1 : Softening Point Test (ASTM D36)
Softening Point ( 0 ˚C)
Number of Test
1
2
Average
Table A.2 : Value of Penetration Index (PI)
PI
Bitumen Type
Checked by : …………………………
Date : ………………………
5
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
SOFTENING POINT OF BITUMEN
8.0 DISCUSSION
9.0 CONCLUSION
6
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
PENETRATION OF BITUMINOUS MATERIALS
1.0 OBJECTIVE
To examine the consistency of a sample of bitumen by determining the distance in tenths of
a millimeter that a standard needle vertically penetrates the bitumen specimen under known
conditions of loading, time and temperature.
2.0 BACKGROUND
This is the most widely used method of measuring the consistency of a bituminous material
at a given temperature. It is a means of classification rather than a measure of quality. (The
engineering term consistency is an empirical measure of the resistance offered by a fluid to
continuous deformation when it is subjected to shearing stress).
The consistency is a function of the chemical constituents of a bitumen, viz. the relative
proportions of asphaltenes (high molecular weight, responsible for strength and stiffness),
resins (responsible for adhesion and ductility) and oils (low molecular weight, responsible
for viscosity and fluidity). The type and amount of these constituents are determined by the
source petroleum and the method of processing at the refinery.
Penetration is related to viscosity and empirical relationships have been developed for
Newtonian materials. If penetration is measured over a range of temperatures, the
temperature susceptibility of the bitumen can be established. The consistency of bitumen
may be related to temperature changes by the expression ;
log P = AT + K . . . (1)
where ;
P = penetration at temperature T
A = temperature susceptibility (or temperature sensitivity)
K = constant
1
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
PENETRATION OF BITUMINOUS MATERIALS
A Penetration Index (PI) has been defined for which the temperature susceptibility would
assume a value of zero for road bitumens, as given by
PI = 20 (1 – 25 A)
( 1+50 A)
The value of A (and PI) can be derived from penetration measurements at two temperatures,
T1 and T2, using the equation
A = log (pen at T1) – log(pen at T 2)
T1 - T 2
Research has shown that, for conventional paving grade bitumens, the Ring-and-Ball
Softening Point temperature is the same as that which would give a penetration of 800 dmm. This, together with the penetration at 25 º C, can be used to compute A where
A = log (pen at 25 º C) – log 800
25 – ASTM softening point
The nomograph as given in Figure 3 enables the PI to be deduced approximately from the
penetration at 25 º C and the softening point temperature. Typical values of PI are
Bitumen Type
PI
Blown Bitumen
>2
Conventional Paving Bitumen
-2 to + 2
Temperature Susceptible Bitumen (Tars)
< -2
2
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
PENETRATION OF BITUMINOUS MATERIALS
PI values can be used to determine the stiffness (modulus) of a bitumen at any temperature
and loading time. It can also, to a limited extent, be used to identify a particular type of
bituminous material. One drawback of the PI system is that it uses the change in bitumen
properties over a relatively small range of temperatures to characterize bitumen;
extrapolations to extremes of the behavior can sometimes be misleading.
3.0 SUMMARY OF THE TEST METHOD
The sample is melted and cooled under controlled conditions. The penetration is measured
with a penetrometer by means of which a standard needle is applied to the bitumen
specimen under specific conditions.
3
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
PENETRATION OF BITUMINOUS MATERIALS
Draw a line between the softening point (line
'A') and penetration (line 'B') values. The
intercept on line 'C' is the PI of the bitumen
Figure 1. Nomograph for the Penetration Index of bitumen (Whiteoak, 1990)
4
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
PENETRATION OF BITUMINOUS MATERIALS
4.0 PROCEDURE
The penetration apparatus (Figure 4) is specified in many standards throughout the world
but has always the same basic requirements as ASTM D5.
1. Specimens are prepared in sample containers exactly as specified (ASTM D5-97) and
placed in a water bath at the prescribed temperature of test for 1 to 1.5 hours before the
test.
2. For normal tests the precisely dimensioned needle, loaded to 100 ± 0.05 g, is brought to
the surface of the specimen at right angles, allowed to penetrate the bitumen for 5 ± 0.1s,
while the temperature of the specimen is maintained at 25 ± 0.1 oC. The penetration
measured in tenths of a millimetre (deci-millimetre, dmm).
3. Make at least three determinations on the specimen. A clean needle is used for each
determination. In making repeat determinations, start each with the tip of th needle at
least 10 mm from the side of the container and at least 10 mm apart.
Figure 4. Apparatus for the bitumen penetration test
5
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
PENETRATION OF BITUMINOUS MATERIALS
5.0 RESULTS
The results are very sensitive to test conditions and bitumen specimen preparation and the
requirement s of the appooprite standards must be rigidly adhered to the maximum
difference between highest and lowest reading shall be :
Penetration (d-mm)
Maximum Difference
0-49
50-149
150-249
250-500
2
4
12
20
6.0 DISCUSSION
a) Report the possible grade of bitumen.
b) Discuss two precautionary measures taken during the experiment.
c) Comment on the difference between the highest and lowest readings and if sub-standard
offer explanation.
d) Calculate the PI and comment on the value obtained. (make sure the penetration and
softening values are obtained from the same batch of bitumen.
.
7.0 REFERENCES
1. ASTM (1998). ASTM D5-97 Standard test method for penetration of bituminous
materials. 1998 Annual Book of ASTM Standards, Volume 04.03, American Society for
Testing and Materials, Philadelphia 19103-1187.
2. Whiteoak, D. (1990). Shell Bitumen Handbook. Shell Bitumen UK, London.
6
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
PENETRATION OF BITUMINOUS MATERIALS
8.0 RESULTS AND CALCULATIONS
Table 8.1 : Penetration Test (ASTM D5)
Number of penetration
Penetration (mm)
1
2
3
Average
Table 8.2 : The difference of highest and lowest reading of penetration
Highest Penetration
(mm)
Lowest Penetration
(mm)
Cheked by : ……………………………….
Difference
(mm)
Date : …………………………………..
7
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
PENETRATION OF BITUMINOUS MATERIALS
9.0 DISCUSSION
10.0 CONCLUSION
8
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE SHAPE TEST
(FLAKINESS INDEX & ELONGATION INDEX)
1.0 INTRODUCTION
The particle shape of aggregates is determined by the percentages of flaky and elongation
particles. Flaky and elongation particles are considered undesirable as they cause weakness
of the pavement. Rounded aggregates are preferred in cement concrete pavements as the
workability of concrete improves. Regular shapes of particles are desirable for granular
base course due to increased stability desired from better interlocking. When the shape of
aggregates deviates more from the spherical shape, as in the case of angular, flaky and
elongation aggregate the void content increase and hence the grain size distribution of the
aggregates has to be suitable altered in order to obtain minimum voids in the dry mix on the
maximum density.
2.0 OBJECTIVE
To determine the flakiness and elongation indices of the given aggregate sample.
3.0 FLAKINESS INDEX
Aggregate particles are classified as flaky when they have a thickness (smallest dimension)
of less than 0.6 of their mean sieve size. The flakiness index of an aggregate sample is
found by separating the flaky particles and expressing their mass as a percentage of the
mass of the sample tested. This test is not applicable to aggregate passing 6.30mm sieve and
retained as 63.0 mm sieve.
1
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE SHAPE TEST
(FLAKINESS INDEX & ELONGATION INDEX)
3.1 Apparatus
1. Metal thickness gauge (Figure 1.0)
2. Test sieve, balance, trays, etc.
Figure 1.0 Shape Test Apparatus
3.2 Procedure
1. The sieve sample with sieves mentioned in Table 7.1. Weight each of the
individual size fraction (w1, w2, w3…..)retained on these sieve, other than the
63.0 mm sieve and store them in separate trays marked with their size.
2. Gauge each fraction from the respective slots in the thickness gauge weigh
pieces which pass through the slots (x1, x2, x3…..etc).
3.3 Calculations and Results.
Flakiness index = x1 + x2 + x3 + ….
x 100
w1 + w2 + w3 + ….
Where x1, x2,…etc. are the weight of the fractions passing from the thickness gauge.
w1, w2…etc are the weight of the original sample retained as the corresponding sieve
2
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE SHAPE TEST
(FLAKINESS INDEX & ELONGATION INDEX)
4.0 ELONGATION INDEX
Aggregate particles are classified as elongation when they have a length (greatest
dimension) of more than 1.8 of their mean sieve size. The elongation index is found by
separating the elongation particles and expressing their mess as a percentage of the mass of
sample tested. The test is not applicable to material passing 6.30 mm sieve or retained on
50 mm sieve.
4.1 Apparatus
1.
Metal length gauge
2.
Sieve
3.
Balance
4.
Tray
4.2 Procedure
1.
Sieve the sample with sieve mentioned in table (3) weight each of the individual
size fractions (w1, w2, w3…. Retained on these sieves other than the 50.0 mm
sieve.
2.
Gauge each fraction as follows, select the length gauge appropriate to the single
fraction under test and gauge each particle separately by hand. Elongated
particles are those whose greatest dimension prevent them from passing through
the gauge. Weigh each fraction which doesn’t pass through the gauge (y1, y2,
…etc)
4.3 Calculation and Results
Elongation index = x1 + x2 + x3 + ….
x 100
w1 + w2 + w3 + ….
Where: y1, y2, y3, ….weight of the fractions not passing through the length gauge
w1, w2, w3,….are the weight of the original sample on the corresponding sieve.
3
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE SHAPE TEST
(FLAKINESS INDEX & ELONGATION INDEX)
Aggregate Shape Test
Size of aggregate
Passing through
IS sieve, mm
Retained on
IS sieve, mm
Width of the
friction
contesting of at
last 200 piece, g
1
63
50
37.5
28
20
14
10
Total
2
50
37.5
28
20
14
10
6.3
3
W1mm….
W2mm….
W3mm….
W4mm….
W5mm….
W6mm….
W7mm….
Flakiness index
=
x1 + x2 + x3 + ….
Weight on
aggregate in each
fraction passing
thickness gauge,
g
4
X1mm….
X2mm….
X3mm….
X4mm….
X5mm….
X6mm….
X7mm….
x 100
w1 + w2 + w3 + ….
Elongation index =
x1 + x2 + x3 + ….
w1 + w2 + w3 + ….
4
x 100
Weight on
aggregate in
each fraction
retained on length
gauge, g
5
Y1mm….
Y2mm….
Y3mm….
Y4mm….
Y5mm….
Y6mm….
Y7mm….
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE SHAPE TEST
(FLAKINESS INDEX & ELONGATION INDEX)
Table 2 data for Determination of Flakiness Index
Aggregate Size Fraction
Width of slot in
Minimum mass for
thickness Gauge or
subdivision
BS test sieve nominal aperture size
special sieve
100% passing
100% retained
mm
mm
mm
kg
63.0
50.0
33.9 ± 0.3
50
50.0
37.5
26.3 ± 0.3
35
37.5
28.0
19.7 ± 0.3
15
28.0
20.0
14.4 ± 0.15
5
20.0
14.0
10.2 ± 0.15
2
14.0
10.0
7.2 ± 0.1
1
10.0
6.3
4.9 ± 0.1
0.5
This dimension is equal to 0.6 times the mean test sieve size
Table 3 data for Determination of Elongation Index
Aggregate Size Fraction
Width of slot in
Minimum mass for
BS test sieve nominal aperture size
thickness Gauge or
subdivision
special sieve
100% passing
100% retained
mm
mm
mm
kg
50.0
37.5
78.7 ± 0.3
35
37.5
28.0
59.0 ± 0.3
15
28.0
20.0
43.2 ± 0.15
5
20.0
14.0
30.6 ± 0.15
2
14.0
10.0
21.6 ± 0.2
1
10.0
6.3
14.7 ± 0.2
0.5
This dimension is equal to 1.8 times the mean test size.
REFERENCES
British Standards Methods of determination of particle shape BS 812, Part 105, 1989.
Kenneth N. derucher and George P .Korfiatis, Material for civil and highway engineers, Prentice
Hall, NJ 2nd edition, 1988.
Harold N. Attkins, Highway materials, soils and concretes, 3rd edition, Prentice Hall, 1990.
5
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE SHAPE TEST
(FLAKINESS INDEX & ELONGATION INDEX)
5.0 RESULT & ANALYSIS
Summary of Flakiness & Elongation Index Test (BS 812 Part: III)
Passing
Sieve
(mm)
63
Retained
Sieve
(mm)
Sample
(gm)
Passing
(gm)
Retained
(gm)
Flakiness
Index
Elongation
Index
50
37.5
28
20
14
10
Checked by ; ……………………………………..
6
Date :…………………………..
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE SHAPE TEST
(FLAKINESS INDEX & ELONGATION INDEX)
6.0 DISCUSSION
a) Determine wheather the aggregate tasted meets Malaysian standard requirement
7.0 CONCLUSION
7
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE IMPACT VALUE
1.0 INTRODUCTION
Impact value of an aggregate is the percentage loss pf weight of particles passing 2.36mm
sieve by the application on load by mean of 15 blows of standard hammer and drop under
specified test condition. The aggregate impact value gives a relation measure of the
resistance of an aggregate to sudden shock or impact, which in some aggregates differs
from their resistance to a slowly applied compressive load.
General: Normally the aggregate impact value of base course is 30, bituminous bound
macadam is about 35 and the cement concrete base course is 30.
Significance: The test gives an idea of toughness of the aggregate to resist facture under the
impact of moving loads.
2.0 OBJECTIVE
To determine the aggregate impact value in the laboratory.
3.0 APPARATUS
1. Impact Testing Machine:
Its consists of a cylindrical hammer of 13.5 kg. (30Ibs) sliding freely between two
vertical supports (called guides). Its fall is automatically adjusted to a height of 38cm.
There is a brass plate over which an open cylindrical steel cup of internal diameter
10.2cm and 5cm depth is placed and fixed to the brass plate.
2. Measure: A cylinder of internal diameter 7.5cm and 5cm deep for measure aggregate.
3. Tamping rod of I cm diameter and 23cm long rounded at one end and pointed at the
other end.
3. Sieves: 12.5mm, 10mm and 2.36mm opening.
4. Balance: 5000g capacity.
5. Laboratory oven capable of maintaining a constant temperature up to 110ºC
1
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE IMPACT VALUE
Apparatus for the Aggregate Impact Value Test (Millard, 1993)
4.0 PROCEDURE
1. Sieve the aggregate and obtain the portion passing 12.5mm and retained on 10mm sieve.
2. Wash and dry this aggregate at a constant temperature of 1050C to 1100C and then cool
the sample.
3. Fill this aggregate in the cylindrical measure in 3 layers, tapping each layers 25 times
with the tamping rod. Level the surface tamping road as a using the straight edge.
4. Weight the aggregate in the measure. This weight of the aggregate is used for the
duplicate test on the same material.
5. Transfer the aggregate from the cylindrical measure to the cup in 3 layers and compact
each layer by tamping in 25 strokes with the tamping rod.
6. Release the hammer for fall freely on the aggregate. The test sample is subjected to a
total of 15 blows.
7. Remove the aggregate sample from the cup and sieve through 2.36 mm sieve.
8. Weight the fraction passing the sieve.
2
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE IMPACT VALUE
5.0 FORMS AND CALCULATION
Sample
Weight of cup
(gm)
Weight before
crush
(gm)
Weight retained
2.36 mm sieve
(gm)
Weight passing
2.36 mm sieve
(gm)
A
B
Average
Percent Wear (Average) = _Weight Loss_
Initial Weight
χ 100
Percent Wear (Average)
Checked by ; ……………………………………..
3
Date :…………………………..
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
AGGREGATE IMPACT VALUE
6.0 DISCUSSION
a) Determine wheather the aggregate tested meets Malaysian Standard requirement.
b) Discuss three precautionary measures taken during the experiment.
7.0 CONCLUSION
Ref : BS 812-112 1990
4
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
CALIFORNIA BEARING RATIO TEST
1.0 INTRODUCTION
The California Bearing Ratio (CBR) was developed by California division of highways as a
method of classifying and evaluating soil-sub-grade and base course materials for flexible
pavements. The CBR test is currently used in pavement design for both roads and airfield
pavement. In some methods CBR is used directly and in some others it is converted to
Resilient Modulus MR using the following relation ships.
MR = 1500 x CBR (ibs/in2)
MR = 10340 x CBR (Kpa)
The laboratory CBR test measures the shearing resistance of a crushed aggregate/soil under
controlled moisture and density conditions. The test yields bearing ratio number that is
applicable for the state of crushed aggregate/soil as tested. The CBR is obtained as the ratio
of the unit stress required of effect a certain depth of penetration of the piston (1935 mm)
into a compacted specimen of crushed aggregate/soil at some water content and density to
the standard unit stress required to obtain the same depth of penetration on a standard
sample of crushed stone. Thus.
CBR =
Test unit stress
Standard unit stress ** 100
The CBR is usually base on the load ratio for the penetration of 2-5mm. If the CBR value at
the penetration of 5.0 mm is larger, the test should be repeated. If a second test yields a
larger value of CBR at 5.0 mm penetration then this larger value should be adopted.
The CBR test are usually made on test specimens at optimum moisture content (OMC) for
the crushed aggregate/soil as determined from modified compaction test.
1
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
CALIFORNIA BEARING RATIO TEST
CBR is used to rate the performances of soils used as bases and sub grade. The following
table gives typical rating :
CBR
0.3
3-7
7-20
20-50
>50
General Rating
Very poor
Poor to fair
Fair
Good
Excellence
Uses
Sub-grade
Sub-grade
Sub-base
Base of sub-base
Base
2.0 OBJECTIVE
To determine the CBR value of the given crushed aggregate/soil sample.
3.0 APPARATUS
1. CBR equipment consisting of 152.4 mm diameter and 178 mm height, An extension
collar of a diameter 51 mm, spacer disk of 150.8mm diameter and 61.4 mm height.
2. Mechanical compaction rammer 50.8 mm die, 2.49 kg and capable of free fall of 305
mm.
3. Surcharge weight to simulate the effect of overlaying pavement weight.
4. CBR machine: A compression machine, which can operate at a constant rate of
1.3mm/min. A metal piston of 1935mm2 is attached to it.
2
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
CALIFORNIA BEARING RATIO TEST
4.0 PROCEDURE
1. CBR equipment consisting of 152.4 mm diameter and 178 mm height, An extension
collar of diameter 51 mm, spacer disk of 150.8 mm diameter and 61.4 mm height.
2. Mechanical compaction rammer 50.8 mm die, 2.49 kg and capable of free fall of 305
mm.
3. Surcharge weight to simulate the effect of overlying pavement weight.
4. CBR machine: A compression machine, which can operate at a constant rate of 1.3
mm/min. A metal piston of 1935mm2 is attached to it.
5. The representative crushed aggregate/soil sample is sieved through 20 mm sieve. About
5 kg of crushed aggregate/soil is taken and mixed with optimum moisture content
(OMC).
6. Clamp the mould to the base plate, attach the extension collar and weight. Insert the
spacer disk into the mold and place a coarse filter paper on the top of the disk.
7. Compact the aggregate /soil water mixture into the world in 3 equal layers to give a
height of 127 mm compact each layer in the 10 blows , 30 blows and 65 blows for each
sample.
8. Determine the water content of the crushed aggregate /soil mixture.
9. Remove the extension collar, and using on straight edge, trim the compacted crushed
aggregate/soil even with the top of the mold surface. Remove the spacer disk and
weight the mold with sample.
10. Place the mold with crushed aggregate/soil on the CBR machine and place the
surcharge weight .seat the penetration piston, set the dial gauges for load and
penetration.
11. Apply the loads to the penetration piston at the rate of 1.27mm/min and record the load
at 0.5,1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, and 10.0mm penetration respectively.
3
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
CALIFORNIA BEARING RATIO TEST
5.0 CALCULATION
CBR : Plot the load deformation curve for each specimen. In some cases the initial
penetration takes place without a proportional increase in the resistance to penetration and
the curve may be concave upward. To obtain the true stress-strain relationships, correct the
curve having concave upward shape near the origin by adjusting the location of the origin
by extending the straight the portion of the stress strain curve down ward until it intersects
with x-axis.
Determine the corrected load values at 2.5mm and 5.0 mm and determine the CBR by the
following relationship.
CBR =
Test unit stress
Standard unit stress ** 100
Standard load at 2.5mm is taken 13.2kN and at 5.0mm it is on 20kN
Dry Density:
Weight of the empty mold = A gm
Weight of the mold + soil = B gm
Volume of soil sample
=V
Weight density γ
=B–A
V
Water Content w
Dry Density γd
=
λ
1+w
Plot the CBR vs Dry density and determine the CBR at 95% of maximum dry density and
repeat this value of CBR.
4
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
CALIFORNIA BEARING RATIO TEST
Summary of Test Results
Sample No.
No.of Blows
1
10
2
30
3
65
γd (gm/cmᵌ)
CBR (%)
CBR at 0.95 γdmax : ………………………………
Checked by ; ……………………………………..
Date :…………………………..
6.0 REFERENCES
1. American Association of State Highway and Transportation Officals. AASHTO T-1931990.
2. ASTM D1556-1982
3. The Asphalt Institute. The Asphalt Handbook
4. E.J.Yoder “Principles of – pavement design” John-Wiley & Sons, New York.
5
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
CALIFORNIA BEARING RATIO TEST
7.0 DISCUSSION
8.0 CONCLUSION
6
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
CALIFORNIA BEARING RATIO TEST
DATA SHEET (CBR TEST)
Type of the Test : Soaked/Unsoaked
OMC Date : ……………………… OMC : ……………… γd max : ……………………
Sample
1
No. of Blows
Empty wt. of mould, W1
Wt of mould + wet sample, W2
Volume of sample, V
Wet density γ = ( W2 - W1) / V
Can no.
Wt.of empty can, A
Wt. of can + wet sample, B
Wt. of can + dry sample, C
Water content, W% = [ (B - C) / (C - A)] * 100
Dry Density, γd = γ / ( 1 + W )
7
2
3
Faculty :
Faculty of Civil and Environmental Engineering
Department :
Department of Infrastructure and Geomatic Engineering
Title :
CALIFORNIA BEARING RATIO TEST
CBR TEST – PENETRATION DATA
Load
Penetration
Sample 1
(mm)
Div.
Corrected
Sample 2
Div.
0.0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
8.0
9.0
10.0
8
Corrected
Sample 3
Div.
Corrected